QAAC setting

[pooksahib]

Hi. I've just noticed that in MeGUI there's an option for the 'Extension' field. What difference does it make to the video being created if you choose M4A over MP4-AAC (and vice-versa)? Thank you.

[KarMa]

Should have no effect. But M4A is usually a container for audio only, but audio only MP4 containers play just fine and MP4/M4A are both closely related containers (if not just the same container just named differently). You are going to MUX this into a MKV or MP4 anyway I'm assuming and so matters even less.

[pooksahib]

Great, thanks for that. You assume correct!

[pandy]

KarMa is right - mp4 is extension usually used to signal that this is audio+video, m4a only for audio and m4v only for video - some dedicated audio players may refuse to play audio track if video is present in container - for example foobar2000 was this kind of audio player (for sure in past).

[hello_hello]

For the record, foobar2000 has played the audio in MP4 and MKV files containing video for a while, and it'll run a ReplayGain scan and use the result to losslessly adjust the volume of AAC audio in an MP4 even if it contains video.

I haven't tested it for MP4 yet, but the latest beta now lets you choose which audio stream to play when there's more than one. It works fine for MKVs containing video and multiple audio streams.